diff --git a/Hashtable.c b/Hashtable.c
index 0f32601a..c1e63c05 100644
--- a/Hashtable.c
+++ b/Hashtable.c
@@ -9,6 +9,7 @@ in the source distribution for its full text.
 
 #include <stdlib.h>
 #include <stdbool.h>
+#include <assert.h>
 
 #include "debug.h"